This research is concerned with the physiological and behavioral mechanisms that underlie pathological feeding behaviors such as overeating, undereating, and ingestion of toxic substances. It is concerned, in particular, with the interaction of peripheral feedback systems in the oropharynx, gastrointestinal system and blood stream on the central neurological controls of food intake and body weight. It is also concerned with experiential and nutritional factors as they relate to ingestive behavior. Specifically, studies will be carried out on the effects of cholecystokinin, sham feeding, and vagotomy on feeding in obese and non-obses rats, on the effects of intravenous infusion parameters on feeding in normal and brain damaged rats, on the effects of motivational parameters on feeding behavior, on the short term physiological effects of brain lesions that reduce body weight, on the relationship between nutritional deficiency and lead pica, and on the effects of early nutritional experience on nutritional choices made by animals later in life. These studies will provide a basic research basis for the understanding of human obesity and its control, the lead pica shown by human children, and the ontogeny of specific food preferences.